Three 3-digit numbers have an average of 330. One of the numbers is 245. The other two numbers are both 3-digit numbers.
- What is the total of the three numbers?
- What is the sum of the other two numbers?
- What is the largest possible difference between the other two numbers?
Need a hint?
For part (c), think about which of the two numbers should be as small as possible, and remember a 3-digit number cannot be smaller than 100.
Worked answer
- (a) Total = average × 3 = 330 × 3 = 990
- (b) Other two numbers sum to 990 − 245 = 745
- (c) To make the difference largest, make one number as small as possible: 100. The other is 745 − 100 = 645. Difference = 645 − 100 = 545
Answer: 545
The mistake this question tests
Habit
Average and total
Pupils often give the larger number (645) as the answer, forgetting to subtract the smaller number 100 to find the difference.
How to fix it at home →More PSLE whole numbers questions
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See the answer →Practise PSLE whole numbers until the mistakes stop.
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